Digital color reproduction printing systems typically include digital front-end processors, digital color printers, and post finishing systems (e.g., UV coating system, glosser system, laminator system, etc). These systems reproduce original color onto substrates (such as paper). The digital front-end processes take input electronic files (such as PDF or postscript files) composed of imaging commands and/or images from other input devices (e.g., a scanner, a digital camera) together with their own internal other function processes (e.g., raster image processor, image positioning processor, image manipulation processor, color processor, image storage processor, substrate processor, etc) to rasterize the input electronic files into proper image bitmaps for the printer to print. An operator may be assisted to set up parameters such as layout, font, color, paper, post-finishing, and etc among those digital font-end processes. The printer (e.g., an electrographic printer) takes the rasterized bitmap and renders the bitmap into a form that can control the printing process from the exposure device to writing the image onto paper. The post-finishing system finalizes the prints by adding finishing touches such as protection, glossing, and binding etc.
In an electrophotographic modular printing machine of known type, for example, the Eastman Kodak NexPress 2100 printer manufactured by Eastman Kodak, Inc., of Rochester, N.Y., color toner images are made sequentially in a plurality of color imaging modules arranged in tandem, and the toner images are successively electrostatically transferred to a receiver member adhered to a transport web moving through the modules. Commercial machines of this type typically employ intermediate transfer members in the respective modules for the transfer to the receiver member of individual color separation toner images. In other printers, each color separation toner image is directly transferred to a receiver member.
Electrophotographic printers having multicolor capability are known to also provide an additional toner depositing assembly for depositing clear toner. The provision of a clear toner overcoat to a color print is desirable for providing protection of the print from fingerprints and reducing certain visual artifacts. However, a clear toner overcoat will add cost and may reduce the color gamut of the print; thus, it is desirable to provide for operator/user selection to determine whether or not a clear toner overcoat will be applied to the entire print. In U.S. Pat. No. 5,234,783, issued on Aug. 10, 1993, in the name of Yee S. Ng, it is noted that in lieu of providing a uniform layer of clear toner, a layer that varies inversely in thickness according to heights of the toner stacks may be used instead as a compromise approach to establishing even toner stack heights. As is known, the respective color toners are deposited one upon the other at respective locations on the receiver member and the height of a respective color toner stack is the sum of the toner contributions of each respective color and so the layer of clear toner provides the print with a more even or uniform gloss.
In U.S. Pat. No. 7,236,734 issued Jun. 26, 2007, in the names of Yee S. Ng et al., a method is disclosed of forming a print having a multicolor image supported on a receiver member wherein a multicolor toner image is formed on the receiver member by toners of at least three different colors of toner pigments which form various combinations of color at different pixel locations on the receiver member to form the multicolor toner image thereon; forming a clear toner overcoat upon the multicolor toner image, the clear toner overcoat being deposited as an inverse mask; pre-fusing the multicolor toner image and clear toner overcoat to the receiver member to at least tack the toners forming the multicolor toner image and the clear toner overcoat; and subjecting the clear toner overcoat and the multicolor toner image to heat and pressure using a belt fuser to provide an improved color gamut and gloss to the image.
Color inaccuracies, including misregistration, occur in all printing systems, including the electrophotographic printing systems. The system environment can change when components, such as the fuser roller, change their operational characteristics over time. Typically linearization processes are used to re-calibrate the printer system, in conjunction with the use of other devices, so that the digital front-end processors are more independent from printer behavior changes. However, in the whole color reproduction printing system, which includes both printer and post finishing system (e.g., UV coater, glosser, and etc), the linearization process alone cannot fully correct the whole color reproduction system variability with out effective controls and controlling systems, such as effective registration devices and color measurement systems. Without these controlling systems the resultant colors may be incorrectly shifted (for example, red shift or green shift), and the resulting reproduction may be perceived as unacceptable to the customer. It is important to make corrections and adjustments to recreate the desired perceived images. However, making these changes can be time consuming and expensive using the current control systems, as well as ineffective.
The present invention overcomes this shortcoming by making image control, that incorporates a registration system and related method, more efficient and accurate and allowing it to occur automatically during the printing run. The following invention solves the current problems with image location control in a wide variety of situations, including duplex printing.